APRIL TASKS

• If lawn fertilizer was applied in fall, make one application in spring, in late April or early May, using three-quarters of a pound actual nitrogen per 1,000 square feet.

If no late-fall fertilizer was applied, make two applications in spring: one in early April, the other in late May, using three-quarters of a pound actual nitrogen per 1,000 square feet each time. Apply turf fertilizer that contains at least 30 percent of the nitrogen in a slow-release form.

To fertilize organically, leave grass clippings on the lawn; they can provide half the soil's nitrogen needs. To add more, spread a quarter-inch of compost onto the grass and rake evenly. Or apply organic fertilizers with a nitrogen-phosphorus-potassium ratio of about 3-1-2. These fertilizers release nutrients more slowly than chemical compounds; the benefits will be gradual but last longer.

• Bluegrass should be cut to a height of 2 to 4 inches. Mow often enough that no more than one-third of the grass blade is removed at any one cutting.

• Pre-emergent herbicides can be applied about mid-April for control of crab grass, barnyard grass, foxtail and other annual grassy weeds. Some annual broadleaf weeds such as chickweed, oxalis and prostrate spurge can be controlled with this application.

For organic crab-grass control, mow cool-season turf grass to 3 inches or higher. Research shows that this suppresses crab grass as well as, or better than, herbicides.

Spread corn-gluten meal on established grass to kill weed seeds and seedlings. Avoid any new grass seed, which also could die.

• Turn off the water to the furnace humidifier and replace the filter. Clean and activate a dehumidifier in damp or musty areas. Turn on a basement vent fan attached to a humidistat to remove moisture and odors. Open screened basement windows on warm, dry days to air out the basement. Change or clean the furnace filters. Activate the sump-pump switch to make sure the unit works. Unplug the pump and lift it from the well to make sure the intake ports are not blocked.

• Test smoke and carbon-monoxide detectors. Check the gauges on fire extinguishers to make sure they are fully charged.

• Check ground-fault interrupters using the built-in test buttons. Make sure these devices are in place in inside outlets near water sources and in outdoor outlets. Call an electrician to install them.